All classes that implement SolrConnectorInterface in Search API Solr 8
- class \Drupal\search_api_solr\Plugin\SolrConnector\BasicAuthSolrConnector
- class \Drupal\search_api_solr\Plugin\SolrConnector\StandardSolrConnector
- class \Drupal\search_api_solr\SolrConnector\SolrConnectorPluginBase implements PluginFormInterface, SolrConnectorInterface uses PluginFormTrait